LIVE briefing on my thoughts on why the supercell in Northeast Arkansas produced such a violent tornado that tore through the east side of Jonesboro yesterday. Preliminary indications are an EF3 maybe EF4 tornado. The right entrance region of an upper-level jet streak provided lift and low-level pressure falls which accelerated the low-level jet, blowing up the wind shear available to this storm. Negative buoyancy spreading east under the clouds from a precipitation shield to its west seemed to weaken and back surface winds, further enhancing the low-level shear. Shallow moisture in the northern mode mitigated the tornado production up there.